So it's modelling racial essentialism and stating that stereotypes are actually true in the gameworld. That all halfings are jovial and dextrous by virtue of their race and you're never going to find a clumsy, surly halfling who is built like a brickhouse and can toss you across the room.It is modeling the physiological differences between races. Halflings are nimble and friendly, gaining DEX and CHA in general or hardy and CON. Some other races are nimble, or quick, or have keen sense of balance, or whatever and might also get a DEX bonus, for instance.
I'm sorry - I can't really accept that. I appreciate that Wizards is removing the racial essentialism from the game and letting characters stand with assumptions that their race dictates ability scores when those scores are already an abstract representation of a character and don't need to be limited that way.
I mean, I'm fairly certain that Wizards has stated that this is the case. Or at least people working for them have - that the ugly connections between the real world implications of an orc getting +2 to Strength by virtue of his race was not able to be ignored anymore. Of course that's the reason - there are other good benefits that come from it, but getting rid of the racist foundation that ability score bonuses are built on top of is a good enough reason for them to do it.And there it is: the real reason why WotC went this route IMO.